ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Uneven
ZrSiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references